Radar apparatus and vehicle

ABSTRACT

An object detection apparatus in a vehicle is provided. The object detection apparatus includes one or more sensors configured to detect at least one object located on at least three rows of seats in the vehicle, the one or more sensors being positioned on a ceiling of the vehicle. The object detection apparatus further includes a circuit configured to determine whether or not the at least one object detected is a living-object. A number of the one or more sensors is less than a number of the at least three rows of seats.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/814,595, filed on Mar. 10, 2020, which in turn claims the benefit ofJapanese Patent Applications No. 2019-043775, filed on Mar. 11, 2019,and No. 2019-165429, filed on Sep. 11, 2019. The disclosure of each ofthese documents, including the specifications, drawings and claims, isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a radar apparatus and a vehicle.

BACKGROUND ART

Sensors for detecting occupants in passenger compartments of motorvehicles have been under development in recent years to improve safetyof the motor vehicles. Such sensors are used for air bag control orautomated driving control, for example. In recent years, sensors fordetecting children left behind in passenger compartments of vehicleshave also been proposed.

PTL 1 discloses an occupant detection sensor that is embedded in a seatcushion and/or a headrest of a seat to detect the presence or absence ofan occupant in the seat to control an auxiliary apparatus on the basisof detection information.

CITATION LIST Patent Literature

-   {P67360 05480070.DOC}-   PTL 1-   Japanese Patent Application Laid-Open No. H8-127264

SUMMARY OF INVENTION

One non-limiting and exemplary embodiment of the present disclosurefacilitates providing an improved radar apparatus and vehicle in whichsensors can be installed at reduced cost.

In one general aspect, the techniques disclosed here feature a radarapparatus according to the present disclosure includes: an antennaconfigured to radiate a first electromagnetic wave in a first radiationangle range including a first direction and radiates a secondelectromagnetic wave in a second radiation angle range including asecond direction opposite to the first direction; and a circuitconfigured to detect a first target in the first direction and a secondtarget in the second direction on the basis of a first reflected signalof the first electromagnetic wave and a second reflected signal of thesecond electromagnetic wave, the first reflected signal and the secondreflected signal being received by the antenna.

It should be noted that general or specific aspects may be implementedas a system, an apparatus, a method, an integrated circuit, a computerprogram, or a recording medium, or may be implemented as any selectivecombination of a system, an apparatus, a method, an integrated circuit,a computer program, and a recording medium.

According to a non-limiting and exemplary embodiment of the presentdisclosure, it is possible to provide an improved radar apparatus andvehicle in which sensors can be installed at reduced cost.

Additional benefits and advantages of non-limiting and exemplaryembodiments of the present disclosure will become apparent from thespecification and drawings. The benefits and/or advantages may beindividually provided by some embodiments and features of thespecification and drawings, which need not all be provided in order toobtain one or more identical features.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of a radar apparatus according toEmbodiment 1;

FIG. 2A is a diagram illustrating an example of attachment of the radarapparatus according to Embodiment 1 to a vehicle;

FIG. 2B is a diagram illustrating an example of a detection signalobtained by the radar apparatus according to Embodiment 1;

FIG. 3A is a schematic sectional view of a radar apparatus that is anexample of the radar apparatus according to Embodiment 1;

FIG. 3B is a schematic sectional view of a radar apparatus that is anexample of the radar apparatus according to Embodiment 1;

FIG. 3C is a schematic sectional view of a radar apparatus that is anexample of the radar apparatus according to Embodiment 1;

FIG. 3D is a schematic sectional view of a radar apparatus that is anexample of the radar apparatus according to Embodiment 1;

FIG. 3E is a schematic sectional view of a radar apparatus that is anexample of the radar apparatus according to Embodiment 1;

FIG. 3F is a schematic sectional view of a radar apparatus that is anexample of the radar apparatus according to Embodiment 1;

FIG. 4A is a diagram illustrating an example of arrangement of antennaelements constituting an antenna according to Embodiment 1;

FIG. 4B is a diagram illustrating an example of arrangement of theantenna elements constituting the antenna according to Embodiment 1;

FIG. 5A is a diagram illustrating an example electromagnetic beamradiation pattern of a radar apparatus according to Modification 1;

FIG. 5B is a diagram illustrating an example of arrangement of antennaelements constituting an antenna according to Modification 1;

FIG. 6 is a diagram illustrating an example of attachment of a radarsystem according to Embodiment 2 to a vehicle;

FIG. 7A is a diagram illustrating an example of attachment of a radarsystem according to Embodiment 3 to a vehicle;

FIG. 7B is a diagram illustrating an example of attachment of the radarsystem according to Embodiment 3 to a vehicle;

FIG. 8A is a diagram illustrating another example of attachment of theradar system according to Embodiment 3 to a vehicle;

FIG. 8B is a diagram illustrating another example of attachment of theradar system according to Embodiment 3 to a vehicle;

FIG. 9A is a diagram illustrating another example of attachment of theradar system according to Embodiment 3 to a vehicle;

FIG. 9B is a diagram illustrating another example of attachment of theradar system according to Embodiment 3 to a vehicle;

FIG. 10 is a diagram illustrating another example of attachment of theradar system according to Embodiment 3 to a vehicle;

FIG. 11 is a diagram illustrating an example of attachment of a radarsystem according to Embodiment 4 to a vehicle;

FIG. 12 is a diagram illustrating another example of attachment of theradar system according to Embodiment 4 to a vehicle;

FIG. 13 is a top view illustrating another example of attachment of theradar system according to Embodiment 4 to a vehicle;

FIG. 14 is a diagram illustrating an example of attachment of a radarsystem according to Embodiment 5 to a vehicle;

FIG. 15 is a schematic sectional view of a radar apparatus that is anexample of a radar apparatus according to Embodiment 5;

FIG. 16 is a schematic sectional view of a radar apparatus that isanother example of the radar apparatus according to Embodiment 5;

FIG. 17 is a schematic sectional view of a radar apparatus that isanother example of the radar apparatus according to Embodiment 5;

FIG. 18 is a schematic sectional view of a radar apparatus that isanother example of the radar apparatus according to Embodiment 5;

FIG. 19 is a schematic sectional view of a radar apparatus that isanother example of the radar apparatus according to Embodiment 5;

FIG. 20 is a schematic sectional view of a radar apparatus that isanother example of the radar apparatus according to Embodiment 5;

FIG. 21 is a diagram illustrating an example of attachment of a radarsystem according to a modification of Embodiment 5 to a vehicle;

FIG. 22 is a diagram illustrating another example attachment of a radarsystem according to a modification of Embodiment 5 to a vehicle;

FIG. 23 is a diagram illustrating another example of attachment of aradar system according to a modification of Embodiment 5 to a vehicle;

FIG. 24 is a top view illustrating another example of attachment of aradar system according to a modification of Embodiment 5 to a vehicle;

FIG. 25 is a top view illustrating another example of attachment of aradar system according to a modification of Embodiment 5 to a vehicle;

FIG. 26 is a schematic sectional view of a radar apparatus that is anexample of a radar apparatus according to a modification of Embodiment5;

FIG. 27 is a diagram illustrating an example configuration of a vehiclecontrol system according to Embodiment 6;

FIG. 28 is a flowchart illustrating an example operation of the vehiclecontrol system according to Embodiment 6; and

FIG. 29 is a diagram illustrating an example configuration of a radarsystem according to Embodiment 7.

DESCRIPTION OF EMBODIMENTS

Among sensors, millimeter-wave radars are contactless and thus haveadvantages of high flexibility of installation and, in addition, beingless susceptible to heat or external light. With the use ofmultiple-input-multiple-output (MIMO) technology that uses multipleantennas for transmission and reception, millimeter-wave radars canimprove target search performance.

In an existing radar apparatus, however, electromagnetic beams areradiated in one direction. The term “one direction”, as used herein,refers to a range of ±90° relative to the normal to a surface of theradar apparatus, and splitting an electromagnetic beam into two or morebeams within this range is also included in radiation in “onedirection”. Therefore, it is difficult for an existing radar apparatusto emit electromagnetic beams forward and backward.

For example, to simultaneously detect a front-seat occupant and arear-seat occupant of a vehicle, at least two radar apparatuses need tobe used in combination, and spaces for installation are difficult tomaintain in seats.

For example, in the related-art technique disclosed in PTL 1, theradiation direction of electromagnetic beams from a radar apparatus isone direction, and a plurality of sensors each detect a single occupant.Thus, to detect all occupants, a large number of sensors are necessary,and it is difficult to reduce the installation cost of the sensors.

The following describes embodiments of the present disclosure in detailwith reference to the drawings. The following embodiments are examples,and the present disclosure is not limited to the following embodiments.

Embodiment 1

FIG. 1 is a schematic sectional view of radar apparatus 2 according toEmbodiment 1. FIG. 2A is a diagram illustrating an example of attachmentof radar apparatus 2 according to Embodiment 1 to a vehicle. Asillustrated in FIG. 2A, radar apparatus 2 is attached to a backrestportion of front seat 51 of the vehicle. For example, one of firstdirection 31 and second direction 32 is directed in the forwarddirection of the vehicle, and the other direction is directed in thebackward direction of the vehicle.

Radar apparatus 2 detects whether occupants 41 and 42 are present inseat (front seat) 51 and seat (rear seat) 52, respectively. In thefollowing, detection may be interchangeably referred to as sensing ormeasurement. Radar apparatus 2 radiates electromagnetic beam (firstelectromagnetic wave, first radar signal) 11 and electromagnetic beam(second electromagnetic wave, second radar signal) 12 in two oppositedirections (first direction 31 and second direction 32) with radarapparatus 2 interposed therebetween, respectively. In an example,electromagnetic beam 11 and electromagnetic beam 12 are radiatedsimultaneously. The angle formed by first direction 31 and seconddirection 32 is any value in the range of 90° to 270°. For example, whenthe angle is 180°, electromagnetic beam 12 and electromagnetic beam 11are respectively radiated in the positive and negative directions alongthe x axis. The radiation angle range of electromagnetic beam 11includes first direction 31. The radiation angle range ofelectromagnetic beam 12 includes second direction 32. In an example, theradiation angle range of electromagnetic beam 11 and the radiation anglerange of electromagnetic beam 12 do not intersect.

The present disclosure is hereinafter described, taking an example inwhich seat 51 and seat 52 are front seat 51 and rear seat 52 disposed inthe passenger compartment of the vehicle, respectively. However, in thepresent disclosure, seat 51 and seat 52 may be disposed in an indoorspace of a mobile object other than a vehicle, for example, an airplaneor a ship, or may be disposed in an indoor space of a building otherthan a mobile object, for example, a movie theater or a restaurant.Further, seat 51 and seat 52 may be installed in the same orientation orin different orientations. For example, seat 51 and seat 52 may beinstalled back-to-back.

Radar apparatus 2 radiates electromagnetic beams 11 and 12 forward andbackward, respectively, to distinguishably detect occupant 41 in frontseat 51 and occupant 42 in rear seat 52.

FIG. 2B is a diagram illustrating an example of a detection signalobtained by radar apparatus 2 according to Embodiment 1. The detectionsignal illustrated in FIG. 2B includes a reflected signal from occupant41 in front seat 51 and a reflected signal from occupant 42 in rear seat52.

In an example, occupant 41 in front seat 51 and occupant 42 in rear seat52 are different distances from radar apparatus 2. For example, whenradar apparatus 2 is installed at the position illustrated in FIG. 2A,occupant 41 in front seat 51 is closer to radar apparatus 2 thanoccupant 42 in rear seat 52. In this case, radar apparatus 2 candistinguishably detect a reflected wave (reflected signal) from occupant41 in front seat 51 and a reflected wave (reflected signal) fromoccupant 42 in rear seat 52. When the distance between radar apparatus 2and occupant 41 in front seat 51 and the distance between radarapparatus 2 and occupant 42 in rear seat 52 are substantially the same,radar apparatus 2 may output electromagnetic beams 11 and 12 atdifferent timings.

After the vehicle is parked or during parking of the vehicle, a radar isactivated for several minutes. If the complex signal component of adetection signal at each distance does not fluctuate under influenceother than noise, no occupant (moving object) is considered to bepresent in the passenger compartment.

On the other hand, for example, when an occupant is sleeping in avehicle during parking of the vehicle, a periodic and regular vibrationdue to the breathing and heartbeat of the occupant can be detected by aradar apparatus as a change in complex signal component. Accordingly, asa result of the observation of the complex signal component of adetection signal within a predetermined distance, if no periodic andregular vibration component is detected, the radar apparatus determinesthat no occupant is present in the vehicle.

In an example, a signal processing circuit (not illustrated) connectedto radar chip 8 (see FIG. 3A) stores in a memory element (memory) inadvance reflected signals received in absence of occupants 41 and 42.

In an example, the signal processing circuit (not illustrated) connectedto radar chip 8 (see FIG. 3A) stores in the memory element (memory) inadvance reflected signals received when occupants 41 and 42 aredetermined to be absent, as reference values.

Then, at the time of detection by radar apparatus 2, the signalprocessing circuit (not illustrated) connected to radar chip 8determines whether occupants 41 and 42 are present in seats 51 and 52,respectively, on the basis of received reflected signals and thereflected signals which are stored reference values. This allows radarapparatus 2 to more accurately detect whether occupants 41 and 42 arepresent, compared with when the reflected signals being the storedreference values are not used.

In an example, radar apparatus 2 has a function of a Doppler sensor anddetects, in addition to the distances to plural occupants 41 and 42, therespective movements of plural occupants 41 and 42. For example, as aresult of detecting a movement resulting from at least one of the bodymovement, heartbeat, and breathing of plural occupants 41 and 42, pluraloccupants 41 and 42 can be more reliably detected. When a vehicleequipped with radar apparatus 2 is at a standstill, the vibration of thevehicle is weaker than during movement, and radar apparatus 2 is able tomore accurately detect a fine movement of plural occupants 41 and 42.Accordingly, for example, radar apparatus 2 can also be used as anin-vehicle left-behind warning sensor for detecting a child left behindin any one of front seat 51 and rear seat 52 during parking. The term“standstill” is used to include both a standstill without the engineidling and a standstill with the engine idling.

FIG. 3A is a schematic sectional view of radar apparatus 2 a, which isan example of radar apparatus 2 according to Embodiment 1.

Radar apparatus 2 a includes substrate 6, antenna 7, radar chip(circuit) 8, and radome 9. In FIG. 3A, a portion of radome 9 isillustrated, and the rest is not illustrated.

Substrate 6 is provided with a circuit that implements the function ofradar apparatus 2 a. On a surface of substrate 6, antenna 7 is formedand radar chip 8 is mounted. The surface of substrate 6 on which radarchip 8 is mounted is hereinafter referred to as a top surface (firstsurface). In an example, at least one of electromagnetic beams 11 and 12radiated from antenna 7 and its reflected signal are beams transmittedthrough substrate 6. Substrate 6 is preferably made of a low-losssubstrate material for high frequencies, for example.

Antenna 7 outputs a transmission signal to radiate electromagnetic beams11 and 12 through radome 9. Antenna 7 may be a single antenna or may beconstituted by a plurality of antennas. Antenna 7 may have a MIMOconfiguration including one or more transmission antenna elements andone or more reception antenna elements.

Radar chip 8 generates a transmission signal to be transmitted fromantenna 7, and generates a detection signal based on the reflectedsignal received by antenna 7. In an example, the signal processingcircuit (not illustrated) connected to radar chip 8 determines whetheroccupants 41 and 42 are present, on the basis of the generated detectionsignal. For example, radar chip 8 has a configuration including atransmitter, a receiver, and an analog-to-digital converter (ADC).

Radome 9 protects substrate 6, antenna 7, and radar chip 8, which areprovided in radar apparatus 2 a. The thickness of radome 9 and theinterval between substrate 6 and radome 9 are desirably adjusted so thatthe intensities of electromagnetic beams 11 and 12 to be radiated becomemaximum.

A circuit (for example, a circuit pattern and a mounted component)provided on substrate 6 are not arranged near antenna 7 or in a regionimmediately above and below antenna 7 so as not to block electromagneticbeams 11 and 12. Consequently, as illustrated in FIG. 3A,electromagnetic beams 11 and 12 are radiated to the outside from bothsurfaces of substrate 6, that is, from a front surface (the positivedirection of the x axis) and a rear surface (the negative direction ofthe x axis), through radome 9.

FIG. 3B is a schematic sectional view of radar apparatus 2 b, which isan example of radar apparatus 2 according to Embodiment 1.

Radar apparatus 2 b illustrated in FIG. 3B is different from radarapparatus 2 a illustrated in FIG. 3A in that the thickness of a regionof substrate 6 through which electromagnetic beam 12 is transmitted isreduced to provide cavity 10 in substrate 6. For example, substrate 6 ofradar apparatus 2 b is provided with cavity 10 in the manner illustratedin FIG. 3B. Cavity 10 is provided on the side of substrate 6 opposite tothe side on which antenna 7 is provided. With the configurationillustrated in FIG. 3B, the thickness of a portion of substrate 6through which electromagnetic beam 12 radiated from antenna 7 toward therear surface of substrate 6 is transmitted is smaller than the thicknessof the corresponding portion of substrate 6 of radar apparatus 2 a, andthe loss of electromagnetic beam 12 due to transmission through theinside of substrate 6 can be reduced.

Cavity 10 may extend to an edge of substrate 6. The thickness of radome9 and the interval between substrate 6 and radome 9 are preferablyadjusted so that the intensities of electromagnetic beams 11 and 12 tobe radiated become maximum with consideration of the shape of cavity 10.For example, radome 9 may have formed therein a recess (not illustrated)depending on the position or shape of cavity 10.

FIG. 3C is a schematic sectional view of radar apparatus 2 c, which isan example of radar apparatus 2 according to Embodiment 1.

Radar apparatus 2 c illustrated in FIG. 3C is different from radarapparatus 2 b illustrated in FIG. 3B in that wave director 13 isprovided in cavity 10. The configuration illustrated in FIG. 3C canfurther improve the directivity of electromagnetic beam 12 to beradiated toward the rear surface of substrate 6 (the negative directionof the x axis).

Radar apparatus 2 c illustrated in FIG. 3C is configured such that wavedirector 13 is provided inside cavity 10 of radar apparatus 2 billustrated in FIG. 3B. Likewise, for example, instead of cavity 10being provided in radar apparatus 2 a illustrated in FIG. 3A, the entirethickness of substrate 6 may be adjusted and, further, wave director 13may be provided on the rear surface of substrate 6. This can furtherimprove the directivity of electromagnetic beam 12 to be radiated towardthe rear surface of substrate 6.

Also in radar apparatus 2 c having wave director 13 arranged therein,the thickness of radome 9 and the interval between substrate 6 andradome 9 are preferably adjusted so that the intensities ofelectromagnetic beams 11 and 12 to be radiated become maximum withconsideration of the shapes and positions of wave director 13 and radome9.

FIG. 3D is a schematic sectional view of radar apparatus 2 d, which isan example of radar apparatus 2 according to Embodiment 1.

Radar apparatus 2 d illustrated in FIG. 3D is different from radarapparatus 2 a illustrated in FIG. 3A in that antenna 7 is provided onthe surface (second surface) of substrate 6 opposite to the surface onwhich radar chip 8 is provided. In an example, when radiation from via14 or wiring 15, which is used to connect radar chip 8 and antenna 7 toeach other, is generated, the generated radiation may be handled asradiation included in at least one of electromagnetic beams 11 and 12.

FIG. 3E is a schematic sectional view of radar apparatus 2 e, which isan example of radar apparatus 2 according to Embodiment 1.

Radar apparatus 2 e illustrated in FIG. 3E is different from radarapparatus 2 a illustrated in FIG. 3A in that antenna 72 is provided onthe surface of substrate 6 opposite to the surface on which radar chip 8is provided and in that reflecting plates 16 are provided in substrate6. Reflecting plates 16 are metal plates, for example. While tworeflecting plates 16 are illustrated in FIG. 3E, the number ofreflecting plates 16 may be any number greater than or equal to one (forexample, one, three, or four). With the provision of reflecting plates16, the influence of an electromagnetic beam radiated from one ofantennas 7 and 72 on the other antenna among antennas 7 and 72 can bereduced.

FIG. 3F is a schematic sectional view of radar apparatus 2 f, which isan example of radar apparatus 2 according to Embodiment 1.

Radar apparatus 2 f illustrated in FIG. 3F is different from radarapparatus 2 e illustrated in FIG. 3E in that antennas 7 and 72 areconnected to different ports of radar chip 8.

In radar apparatus 2 f, antenna 7 or 72 is connected to one transmissionport of radar chip 8. Consequently, antenna output can further beenhanced, and the detectable distance can be made longer. Therefore,radar apparatus 2 f may be used to detect danger outside the passengercompartment in addition to detecting occupants in the passengercompartment. In radar apparatus 2 f, furthermore, the outputs ofdifferent antennas 7 and 72 connected to different transmission portscan be easily adjusted separately. In FIG. 3F, each of the transmissionports of radar chip 8 may output a signal of a different pattern.

FIGS. 4A and 4B are diagrams illustrating an example of arrangement ofantenna elements 17 constituting antennas 7 and 72 according toEmbodiment 1.

For example, as illustrated in FIGS. 4A and 4B, the number of antennaelements 17 provided on the front surfaces of antennas 7 and 72 may bedifferent from the number of antenna elements 17 provided on the rearsurfaces of antennas 7 and 72 in accordance with the application ofradar apparatus 2 (2 a to 2 f). This can adjust the antenna gain orviewing angle of antennas 7 and 72 in accordance with the application ofradar apparatus 2 (2 a to 2 f).

(Modification 1)

In radar apparatus 2 (2 a to 2 f) according to Embodiment 1,electromagnetic beams 11 and 12 are radiated in a directionperpendicular to the top surface of substrate 6. In Modification 1, incontrast, electromagnetic beams 11 and 12 are radiated in a directionalong the top surface of substrate 6.

FIG. 5A is a diagram illustrating an example radiation pattern ofelectromagnetic beam 28 of radar apparatus 2 g according toModification 1. FIG. 5B is a diagram illustrating an example ofarrangement of antenna elements 27 a to 27 n constituting antenna 27according to Modification 1.

Radar apparatus 2 g includes substrate 6, radar chip 8, and antenna 27.Substrate 6 has arranged thereon antenna 27 that radiateselectromagnetic beams from either surface (for example, the top surface)of substrate 6 in both right and left directions (the positive andnegative directions of the x axis) along the front surface.

In antenna 27, signals that are 180 degrees out of phase are input totwo antenna elements (for example, antenna elements 27 a and 27 b).Accordingly, as illustrated in the side view in FIG. 5A, electromagneticbeam 28 having directivity in separate, right and left directions ofsubstrate 6 (directions along the top surface of substrate 6: thepositive and negative directions of the x axis), rather than in thezenith direction (a direction perpendicular to the top surface ofsubstrate 6: the positive direction of the z axis), is radiated. Radarapparatus 2 g illustrated in FIGS. 5A and 5B can also be used toconfigure a sensor capable of simultaneously detecting a plurality ofdetection targets (occupants 41 and 42, targets) to the right and leftsides of radar apparatus 2 g.

The arrangement positions, number, and shapes of antenna 27 and antennaelements 27 a to 27 n are not limited to those illustrated in FIGS. 5Aand 5B. For example, the number of antenna elements 27 a to 27 n may beany positive even number.

According to Embodiment 1 or Modification 1, a plurality of occupantscan be simultaneously detected using one radar apparatus 2 (2 a to 2 g),and therefore cost can be reduced compared with the installation of aplurality of sensors or radar apparatuses.

Seats 51 and 52 illustrated in FIG. 2A, radar apparatuses 2 a to 2 gillustrated in FIGS. 3A to 3F and FIGS. 5A and 5B, and antennas 7 and 72and antenna elements 17 illustrated in FIGS. 4A and 4B are merelyexamples, and the shapes and arrangements thereof are not limited to theillustrated ones.

The viewing angle of radar apparatus 2 (2 a to 2 g) may be extended inthe horizontal direction. In addition, radar apparatus 2 may beinstalled such that the radiation direction of electromagnetic beam 11(or electromagnetic beam 12) from radar apparatus 2 is directed towardthe center of rear seat 52 so long as occupant 41 in front seat 51 canbe detected without any difficulty. This allows radar apparatus 2 todetect an occupant seated in the center of rear seat 52.

Embodiment 2

When radar apparatus 2 is attached to seat 51 or 52, the orientations ofelectromagnetic beams 11, 12, and 28 from radar apparatus 2 changes withmovement of seat 51 and/or 52, and it is difficult to detect occupants41 and 42. In other words, the probability of error detection may becomehigh. The movement of seat 51 and/or 52 refers to, for example, theforward or backward slide of seat 51 and/or 52 or a change in theinclination angle of the backrest portion of seat 51 and/or 52 when seat51 and/or 52 is reclined. Embodiment 2 examines difficulty in detectingoccupants 41 and 42 depending on movement of seat 51 and/or 52.

FIG. 6 is a diagram illustrating an example of attachment of radarsystem 3 a according to Embodiment 2 to a vehicle.

Radar system 3 a includes radar apparatus 2 and angle sensor 18.

Radar apparatus 2 according to Embodiment 2 includes components commonto radar apparatus 2 according to Embodiment 1. Radar apparatus 2 may beany one of radar apparatuses 2 a to 2 g illustrated in FIGS. 3A to 3Fand FIGS. 5A and 5B.

Angle sensor 18 detects the orientation of radar apparatus 2. Anglesensor 18 is installed inside or near radar apparatus 2, for example.

Front seat 51 is typically a reclining seat. Front seat 51 in whichradar apparatus 2 is installed has backrest 19 whose angle may bechanged to the angle desired by occupant 41. In accordance with thedegree of inclination of seat 51, the radiation direction of anelectromagnetic beam directed to occupant 42 in rear seat 52 from radarapparatus 2 changes. Consequently, occupant 42 in rear seat 52 may beoutside the detection range of radar apparatus 2 depending on the angleof backrest 19.

Angle sensor 18 stores in advance a range of angles over which it isdifficult for radar apparatus 2 to detect occupant 42. While radarapparatus 2 is in operation, in response to detection that the angle offront seat 51 detected by angle sensor 18 is included in the range ofangles stored in angle sensor 18, angle sensor 18 may output a signalindicating that it is difficult to perform detection (or the detectionresult is invalid). In an example, radar system 3 a may include anotifier (not illustrated) that notifies occupant 41 that it isdifficult to perform detection (or the detection result is invalid) whenangle sensor 18 outputs a signal indicating that it is difficult toperform detection (or the detection result is invalid). The notifier maybe, for example, a monitor viewed by occupant 41 or a speaker providedin the vehicle.

In an example, if front seat 51 is slidable as well as reclinable tomake its forward or backward position adjustable, radar system 3 aincludes a position sensor (not illustrated) that detects the forward orbackward position of front seat 51. In this case, the position sensorstores in advance a range of positions over which it is difficult forradar apparatus 2 to detect occupant 42. While radar apparatus 2 is inoperation, in response to detection that the position of front seat 51detected by the position sensor is included in the range of positionsstored in the position sensor, the position sensor may output a signalindicating that it is difficult to perform detection (or the detectionresult is invalid). This may allow more accurate detection of a statewhere it is difficult for radar apparatus 2 to detect occupants 41 and42.

In an example, furthermore, radar apparatus 2 stores in advance areflected signal from an object arranged inside or outside the passengercompartment. The higher the reflection coefficient the object has, themore preferable it is. For example, the object may be a fixed object,such as the frame of the vehicle body, or a movable object whosemovement is known, such as a rear wiper. Then, at the time of detectionby radar apparatus 2, a signal processing circuit (not illustrated)connected to radar apparatus 2 determines whether it is difficult toperform detection (or the detection result is invalid), on the basis ofa received reflected signal and the stored reflected signal. The signalprocessing circuit detects whether occupants 41 and 42 are present inseats 51 and 52, respectively, on the basis of a difference signalbetween a received reflected signal and the stored reflected signal.This may allow more accurate detection of a state where it is difficultfor radar apparatus 2 to detect occupants 41 and 42. The signalprocessing circuit may be connected to radar chip 8 and arranged insideradar apparatus 2.

Embodiment 3

In Embodiment 2, angle sensor 18 is used to detect a state where it isdifficult for radar apparatus 2 to detect occupants 41 and 42 dependingon movement of seat 51 and/or 52. Embodiment 3 examines any other meansfor detecting a state where it is difficult for radar apparatus 2 todetect occupants 41 and 42 depending on movement of seat 51 and/or 52.

FIGS. 7A and 7B are diagrams illustrating an example of attachment ofradar system 3 b according to Embodiment 3 to a vehicle. Radar system 3b includes radar apparatus 2 and reference marks (first reference mark,reference target) 20. In an example, radar system 3 b further includesangle sensor 18. Among the components of radar system 3 b according toEmbodiment 3, components common to radar system 3 a according toEmbodiment 2 will not be described.

Radar apparatus 2 includes components common to radar apparatus 2according to Embodiment 1. Radar apparatus 2 may be any one of radarapparatuses 2 a to 2 g illustrated in FIGS. 3A to 3F and FIGS. 5A and5B. Further, in response to detection of a reflected signalcorresponding to a reflected wave from reference marks 20, a signalprocessing circuit (not illustrated) connected to radar apparatus 2determines that it is possible to detect seats 51 and 52 (it is notdifficult to perform detection (or the detection result is notinvalid)).

Reference marks 20 reflect electromagnetic beam 11 or electromagneticbeam 12 radiated from radar apparatus 2. In an example, as illustratedin FIG. 7B, reference marks 20 are installed on both sides of rear seat52. It is more preferable that a reflected signal from each of referencemarks 20 have higher intensity than a reflected signal from a humanbody. As illustrated in FIG. 7B, reference marks 20 may be each arectangular metal plate that is bent on one side at an angle of 90°relative to the center axis in the longitudinal direction of therectangular metal plate, for example. The metal plate is installed suchthat reflection surfaces that reflect electromagnetic beam 11 orelectromagnetic beam 12 intersect at an acute angle.

In radar system 3 b according to Embodiment 3, the signal processingcircuit (not illustrated) connected to radar apparatus 2 can determinewhether it is difficult for radar apparatus 2 to perform detection (orthe detection result is invalid), on the basis of a reflected signalfrom reference marks 20. While reference marks 20 illustrated in FIGS.7A and 7B are installed on both sides of rear seat 52, the shapes,installation positions, and number of reference marks 20 are notlimited.

FIGS. 8A and 8B are diagrams illustrating another example of attachmentof radar system 3 b according to Embodiment 3 to a vehicle. For example,as illustrated in FIGS. 8A and 8B, reference mark 20, which is arectangular metal plate, may be arranged in such a manner that itslongitudinal direction extends in the horizontal direction.

When reference mark 20 is arranged in the manner illustrated in FIGS. 8Aand 8B, reference mark 20 is less likely to be hidden by occupant 42 anda load (not illustrated) in rear seat 52 from radar apparatus 2 thanreference marks 20 illustrated in FIGS. 7A and 7B. This can reducepotential detection errors indicating that “it is difficult to performdetection (or the detection result is invalid)” due to difficulty inobtaining a reflected signal from reference mark 20 because referencemark 20 is hidden by occupant 42 and a load.

The number and positions of reference marks 20 whose longitudinaldirections extend in the horizontal direction are not limited to thoseillustrated in FIGS. 8A and 8B.

FIGS. 9A and 9B are diagrams illustrating another example of attachmentof radar system 3 b according to Embodiment 3 to a vehicle. In anexample, as illustrated in FIGS. 9A and 9B, radar system 3 b furtherincludes radio-wave absorber 21.

As illustrated in FIGS. 9A and 9B, radio-wave absorber 21 is arranged onthe back of reference mark 20, for example. This allows radar apparatus2 to more easily distinguish a reflected signal from reference mark 20and a reflected signal from a structure installed near reference mark 20from each other, and thus a reflected signal from reference mark 20 canbe more reliably identified.

The shape and position of radio-wave absorber 21 are not limited tothose illustrated in FIGS. 9A and 9B so long as radar apparatus 2 isable to easily distinguish a reflected signal from reference mark 20 anda reflected signal from a structure installed near reference mark 20from each other. Reference mark 20 may be a combination of at least oneof reference marks 20 illustrated in FIGS. 7A and 7B, FIGS. 8A and 8B,and FIGS. 9A and 9B.

FIG. 10 is a diagram illustrating another example of attachment of radarsystem 3 b according to Embodiment 3 to a vehicle. In an example, asillustrated in FIG. 10 , radar system 3 b further includes referencemark (second reference mark, reference target) 22.

Reference mark 22 reflects electromagnetic beam 11 or electromagneticbeam 12 radiated from radar apparatus 2. In an example, as illustratedin FIG. 10 , reference mark 22 is installed in a ceiling portion or afloor portion of the passenger compartment. It is more preferable that areflected signal from each of reference marks 22 have higher intensitythan a reflected signal from a human body. As illustrated in FIG. 10 ,reference marks 22 may be each a rectangular metal plate that is bent onone side at an angle of 90° relative to the center axis in thelongitudinal direction of the rectangular metal plate, for example. Themetal plate is installed such that reflection surfaces that reflectelectromagnetic beam 11 or 12 intersect at an acute angle.

When radar apparatus 2 detects a reflected signal from reference marks22, the signal processing circuit (not illustrated) connected to radarapparatus 2 determines that it is difficult to perform detection. Thisallows the signal processing circuit (not illustrated) connected toradar apparatus 2 to determine whether it is difficult for radarapparatus 2 to perform detection (or the detection result is invalid),on the basis of a reflected signal from reference marks 22.

The number, shapes, and positions of reference marks 22 are not limitedto those illustrated in FIG. 10 . Furthermore, reference marks 22 may beeach implemented as a fixed object installed in the passengercompartment illustrated in FIG. 10 or a movable object whose movement isknown.

The shape and position of radio-wave absorber 21 are not limited tothose illustrated in FIGS. 9A and 9B so long as radar apparatus 2 isable to easily distinguish a reflected signal from reference marks 22and a reflected signal from a structure installed near reference mark 20from each other.

Embodiment 4

This embodiment describes radar system 3 including two radar apparatuses2 to sense occupants in a vehicle having three rows of seats.

FIG. 11 is a diagram illustrating an example of attachment of radarsystem 3 c according to Embodiment 4 to a vehicle. In radar system 3 cillustrated in FIG. 11 , two radar apparatuses 2 are arranged in avehicle having three rows of seats. Radar apparatuses 2 have a functionof applying at least an electromagnetic beam (radar signal, transmissionsignal) toward an occupant in the passenger compartment and are arrangedin the ceiling of the passenger compartment. Radar apparatuses 2 applyelectromagnetic beams to occupants 41, 42, and 43, thereby performingoccupant sensing.

Two radar apparatuses 2 are arranged above the first-row seat and abovethe third-row seat. Accordingly, radar apparatus 2 above the first-rowseat has a detection range covering the first-row seat and thesecond-row seat, and radar apparatus 2 above the third-row seat has adetection range covering the third-row seat and a cargo space behind thethird-row seat.

FIG. 12 is a diagram illustrating another example of attachment of radarsystem 3 d according to Embodiment 4 to a vehicle. In radar system 3 dillustrated in FIG. 12 , two radar apparatuses 2 are arranged in avehicle having three rows of seats. FIG. 12 illustrates an example ofarrangement of radar apparatuses in which sunroof 4 arranged above thefirst-row seat is taken into consideration. Two radar apparatuses 2 arearranged near a head console, which is located in front of and above thefirst-row seat, and above the second-row seat. Accordingly, radarapparatus 2 near the head console located in front of and above thefirst-row seat has a detection range covering the first-row seat, andradar apparatus 2 above the second-row seat has a detection rangecovering the second-row seat and the third-row seat.

FIG. 13 is a top view illustrating another example of attachment ofradar system 3 e according to Embodiment 4 to a vehicle. In radar system3 e illustrated in FIG. 13 , two radar apparatuses 2 are arranged in avehicle having three rows of seats.

FIG. 13 illustrates an example of arrangement of radar apparatuses 2when sunroof 4 arranged above the first-row seat is taken intoconsideration. Sunroof 4 is indicated by a dotted line. Radarapparatuses 2 are arranged at a position, which is offset relative tothe first-row seat in the positive direction of the y axis such that theposition is shifted away from sunroof 4, and at a position above thethird-row seat. Accordingly, radar apparatus 2 at a position shiftedaway from sunroof 4 has a detection range covering the first-row seatand the second-row seat, and radar apparatus 2 above the third-row seathas a detection range covering the third-row seat and the cargo spacebehind the third-row seat.

The example arrangements illustrated in FIGS. 12 and 13 may be used evenwhen sunroof 4 is not installed. Since sunroof 4 is an optional part,changing the arrangement of radar apparatuses 2 depending on whethersunroof 4 is installed results in an increase in production cost. Incontrast, radar apparatuses 2 are fixedly arranged, regardless ofwhether sunroof 4 is installed, leading to a reduction in productioncost. The examples of the arrangement of radar apparatuses 2 illustratedin FIGS. 12 and 13 may also be applied to a vehicle having two rows ofseats.

Embodiment 5

This embodiment describes a radar system including one radar apparatus 2to sense occupants in a vehicle having three rows of seats.

FIG. 14 is a diagram illustrating another example of attachment of radarsystem 3 f according to Embodiment 5 to a vehicle. In radar system 3 fillustrated in FIG. 14 , one radar apparatus 2 is arranged in a vehiclehaving three rows of seats.

An antenna of radar apparatus 2 has a wide viewing angle to applyradiation to occupants 41, 42, and 43. Accordingly, radar apparatus 2 isfurther equipped with an antenna for occupants 41 and 42, whosedirectivity is adjusted, in addition to an antenna for occupant 42.

FIG. 15 is a schematic sectional view of a radar apparatus that is anexample of a radar apparatus according to Embodiment 5. In FIG. 15 ,radar apparatus 2 h has a configuration in which a radome is arranged tosurround substrate 6. Radar apparatus 2 h illustrated in FIG. 15 may usea portion of radome 9 as a concave lens to broaden the viewing angle ofbeams. In this embodiment, as in FIGS. 3A to 3F, substrate 6 has antenna7 and radar chip 8 mounted thereon, which will not be described orillustrated here.

FIG. 16 is a schematic sectional view of radar apparatus 2 i, which isanother example of the radar apparatus according to Embodiment 5. InFIG. 16 , reflectors 80, 81, 82, and 83 (also be referred to asreflecting plates) may be provided to direct electromagnetic beams tooccupants 41 and 43 from antenna elements 17 (not illustrated) arrangedon substrate 6. In FIG. 16 , antenna elements 17 arranged on substrate 6transmit and receive direct waves to and from occupant 42.

FIG. 17 is a schematic sectional view of radar apparatus 2 j, which isanother example of the radar apparatus according to Embodiment 5. InFIG. 17 , radome 9 is arranged to surround substrate 6, and preferablyhas a configuration in which a surface (surface facing in the negativedirection of the z axis) of radome 9 is shaped with concavity andconvexity such that a radio wave can be scattered in various directions.The shape with concavity and convexity may be a periodic uniform shape,as illustrated in FIG. 17 , or may be an irregular, random shape. Radome9 may not cover all of substrate 6 and may be arranged to have a shapewith concavity and convexity at least on a side thereof from which anelectromagnetic beam is radiated.

FIG. 18 is a diagram illustrating another example of radar apparatus 2according to Embodiment 5. FIG. 19 is a diagram illustrating anotherexample of radar apparatus 2 according to Embodiment 5.

In radar apparatus 2 k illustrated in FIG. 18 , a drive section (notillustrated) is used to physically change the orientation of radarapparatus 2 k in a periodic manner so that occupants 41 to 43 are withinthe viewing angle. Each occupant is sensed in accordance with thisperiod, thereby sensing occupants 41, 42, and 43 even if the viewingangle of radar apparatus 2 is small. As illustrated in FIG. 19 , radarapparatus 2L may be driven by a drive section (not illustrated) totranslate in the forward and backward directions. Advantages effectssimilar to those in FIG. 18 are achieved.

FIG. 20 is a diagram illustrating another example of radar apparatus 2according to Embodiment 5. In FIG. 20 , radar apparatus 2 is attachedabove the second-row seat such that electromagnetic beams are appliedboth toward occupant 42 (the negative direction of the z axis) andtoward the ceiling (the positive direction of the z axis) from radarapparatus 2. Reflector 86 is installed at a position closer to theceiling than radar apparatus 2 to split a beam into the forward andbackward directions of the passenger compartment.

Reflector 86 has at least two reflection surfaces facing in the forwarddirection (the negative direction of the x axis) and the backwarddirection (the positive direction of the x axis), and the reflectionsurfaces are desirably made of metal and concave. The concave surfacesof reflector 86 can be each implemented using, for example, a portion ofa paraboloid.

Reflectors 87 and 88 are installed in front of and behind reflector 86.Each of reflectors 87 and 88 desirably has a metal reflection surface,and the reflection surfaces of reflectors 87 and 88 are desirablyprocessed into a flat or concave shape such that electromagnetic beamsare reflected toward occupants 41 and 43. Furthermore, reflectors 87 and88 are desirably arranged such that path lengths of electromagneticbeams from radar apparatus 2 to occupants 41 and 43 are different.

With the configuration described above, each of occupants 41, 42, and 43in the three rows of seats is associated with a path length of anelectromagnetic beam, thereby facilitating sensing using one radarapparatus 2.

Modification of Embodiment 5

This embodiment describes a radar system that uses one radar apparatus 2and a reflector to sense occupants in a vehicle having three rows ofseats.

FIG. 21 is a diagram illustrating an example of attachment of radarsystem 3 g according to a modification of Embodiment 5 to a vehicle. InFIG. 21 , radar system 3 g uses the windshield as reflector 84.

In FIG. 21 , an occupant in the first-row seat is sensed by utilizing amultipath radio wave, which is a reflected wave component from thewindshield (the reflector 84). A radio wave beam radiated from radarapparatus 2 is reflected from the windshield (the reflector 84) and isthen reflected from the occupant in the first-row seat. The radio wavebeam reflected from the occupant is reflected again from the windshield(the reflector 84), and a multipath radio wave is received by radarapparatus 2. Accordingly, radar system 3 g illustrated in FIG. 21detects occupant 41 in the first-row seat as an object at a positionfarther than the actual distance between the first-row seat and radarapparatus 2.

Radar apparatus 2 determines whether occupant 41 is present, using, asdetermination criteria, whether a reflective object (occupant 41) ispresent at a position that takes into consideration in advance theincrease in distance caused by reflection and whether a reflection pointon the windshield matches an angle that takes into consideration theposition of radar apparatus 2.

The reflected wave from the windshield is input to radar apparatus 2from an end (closer to the end-fire), compared with a direct reflectedwave from occupant 41 in the first-row seat.

Radar system 3 g may use, for example, a rear-view mirror, side-viewmirrors, or the like in place of the windshield serving as reflector 84illustrated in FIG. 21 . A rear-view mirror and side-view mirrors areadjusted at an angle visible to the driver to allow the driver to have aclear view of the rear of the vehicle. Accordingly, radar apparatus 2 isarranged above the second-row seat behind the driver, thereby allowingradar apparatus 2 to receive an electromagnetic beam reflected by therear-view mirror.

In radar system 3 g, a weak reflected wave is considered to be input toan occupant seated in the front passenger's seat from the rear-viewmirror. For the occupant seated in the front passenger's seat,accordingly, the installation position of radar apparatus 2 may beoffset toward either the front passenger's seat or the driver's seatwith respect to the center to adjust the intensity of a reflected wavefrom the corresponding side-view mirror. For the occupant seated in thefront passenger's seat, alternatively, a reflector other than a mirrormay be provided in the vehicle.

FIG. 22 is a diagram illustrating another example of attachment of aradar system according to a modification of Embodiment 5 to a vehicle.In FIG. 22 , radar system 3 h has a rear-view mirror (reflector 85)arranged near the head console. The head console is located above thefirst-row seat, thereby facilitating detection of an occupant in thefirst-row seat compared to when a reflected wave from the windshield isused.

Reflector 85, which is arranged near the head console, may be a singlereflector to split and reflect an electromagnetic beam (radar signal)into the right and left seats, or reflectors 85 may be arranged for theright and left seats. This can increase the intensity of reflectedsignals from the respective seats, resulting in more accurate receptionof the reflected signals. When reflectors 85 are arranged for the rightand left seats, reflectors 85 are arranged to be offset from radarapparatus 2 to provide a difference in path length, thereby facilitatingthe determination of reflected waves (reflected signals) from the rightand left seats.

Other examples of the reflector (reflecting plate) may include reflector85 that is arranged in an attachment portion of the rear-view mirror.

FIG. 23 is a diagram illustrating another example of attachment of radarsystem 3 j according to a modification of Embodiment 5 to a vehicle. InFIG. 23 , radar apparatus 2 is arranged above the first-row seat,thereby having a detection range covering the first-row seat and thesecond-row seat. Further, reflector 89 is arranged above the third-rowseat, thereby allowing radar apparatus 2 to have a detection rangecovering the third-row seat.

FIG. 24 is a top view illustrating another example of attachment ofradar system 3 k according to a modification of Embodiment 5 to avehicle. In FIG. 24 , radar apparatus 2 is arranged near the headconsole located in front of and above the first-row seat, thereby havinga detection range covering the first-row seat. Further, reflectors 80 aand 80 b are arranged in the left and right edges of the ceiling of thevehicle, thereby allowing radar apparatus 2 to have a detection rangecovering the second-row seat and the third-row seat. In FIG. 24 , longand narrow reflectors 80 a and 80 b are used. Alternatively, a pluralityof reflectors having a smaller area may be arranged.

Reflectors 80 a and 80 b may be shaped such that, for the second-rowseat and the third-row seat, electromagnetic beams from radar apparatus2 to reflectors 80 a and 80 b are transmitted in parallel to the ceilingand the directions of the electromagnetic beams are changed fromreflectors 80 a and 80 b to the desired seats.

Furthermore, with the use of long and narrow reflectors 80 a and 80 b,even when the second-row seat and the third-row seat slide, a radarsignal from radar apparatus 2 can be reflected by the occupants in thesecond-row seat and the third-row seat.

FIG. 25 is a top view illustrating another example of attachment ofradar system 3L according to a modification of Embodiment 5 to avehicle. In FIG. 25 , radar apparatus 2 is arranged to be offsetrelative to the first-row seat in the positive direction of the y axis,thereby having a detection range covering the first-row seat. Further,reflector 80 c is arranged in the left edge of the ceiling of thevehicle (the negative direction of the y axis), thereby allowing radarapparatus 2 to have a detection range covering the second-row seat andthe third-row seat. In FIG. 25 , reflector 80 c may be arranged abovethe first-row seat such that an occupant in the first-row left seat isdetected using a reflected signal.

Reflector 80 d may further be arranged in the right edge of the ceiling(the positive direction of the y axis). Radar apparatus 2 may detect anoccupant by a reflected wave that is reflected from reflector 80 c inthe left edge of the ceiling and that is further reflected fromreflector 80 d. In this case, reflector 80 c may have a configurationincluding a portion in which the reflected wave is reflected toward thereflector 80 d, and a portion in which the reflected wave is reflectedtoward the desired seat.

In the configuration illustrated in FIGS. 23, 24, and 25 , the use of areflector allows a radar apparatus to detect occupants in the second-rowseat and the third-row seat. Even a child whose sitting height issmaller than the height of the backrest can be detected.

FIG. 26 is a schematic sectional view of radar apparatus 2 m, which isanother example of the radar apparatus according to Embodiment 5. Inradar system 3 illustrated in FIGS. 23, 24, and 25 , the radiationdirection of radar apparatus 2 is a direction that is substantiallyhorizontal to the ceiling. For example, when radar apparatus 2 has aviewing angle of 160°, radar apparatus 2 is inclined in the positivedirection of the z axis at an angle of 10°, thereby horizontallyradiating a radar signal to the rear of radar apparatus 2.

As described above, with the use of a reflector, even one radarapparatus can detect occupants in three rows of seats.

Embodiment 6

This embodiment describes switching between a mode (object sensing mode)of sensing the presence of an object (occupant) and a mode(living-object sensing mode) of sensing a fine movement caused by aheartbeat and the like. In the foregoing embodiments, description hasbeen made on the assumption that the target detected by a radarapparatus is an occupant. In this embodiment, a determination is made ofwhether the target detected by a radar apparatus is a load or a livingobject, and a radar apparatus is described as sensing an object.

FIG. 27 is a diagram illustrating a configuration of vehicle controlsystem 92 according to Embodiment 6. FIG. 28 is a flowchart illustratingan example operation of vehicle control system 92 according toEmbodiment 6.

Vehicle control system 92 includes radar system 3, vehicle controlapparatus 90, and seat-belt wearing check apparatus 91. Radar system 3includes one or more radar apparatuses 2 described in the otherembodiments, mode switch 25 that switches between the object sensingmode and the living-object sensing mode, and determiner 24 thatdetermines whether the object sensed by radar apparatus 2 in theliving-object sensing mode is a living object. Radar system 3 determinesthe presence or absence of a load in a vehicle or the presence orabsence of a living object in the vehicle.

Vehicle control apparatus 90 emits a warning to the driver on a display(not illustrated) using an output signal of radar apparatus 2 and anoutput signal of seat-belt wearing check apparatus 91 or controls, forexample, a light, a door lock, a communication apparatus, and anair-conditioning apparatus installed in the vehicle, which are notillustrated, using an output signal of radar apparatus 2 and an outputsignal of seat-belt wearing check apparatus 91.

Seat-belt wearing check apparatus 91 outputs a signal indicating adetermination of whether a tongue plate of each seat belt (notillustrated) has been inserted into its corresponding buckle.

First, mode switch 25 receives, as information about movement of thevehicle, information indicating that the engine has been started afteroccupants have entered the vehicle (start of driving) or receives,during movement of the vehicle, information indicating no change in thenumber of occupants when the vehicle is at a standstill such as at anintersection stop light or because of a traffic jam (restart of driving)(S101). Then, mode switch 25 outputs to vehicle control apparatus 90that radar system 3 operates in the object sensing mode.

Radar apparatus 2 outputs a radar signal and receives a reflected waveto determine whether an object is present in each seat (S102). If radarapparatus 2 detects the presence of an object (YES in S103) andseat-belt wearing check apparatus 91 detects that a seat belt is notworn (NO in S104), vehicle control apparatus 90 generates a seat-beltwarning (S105).

Vehicle control apparatus 90 may not check whether a seat belt is wornfor a seat in which no object is present. That is, vehicle controlapparatus 90 performs the object sensing mode until a determination asto whether to generate a seat-belt warning is finished for all the seats(NO in S103).

The object sensing mode is a mode of sensing the presence or absence ofan object, and even a large load or the like is not distinguished froman occupant (living object). Accordingly, when the vibration of thevehicle is weak, such as before the vehicle starts or when the vehicleis at a standstill such as at an intersection stop light or because of atraffic jam, mode switch 25 switches from the object sensing mode to theliving-object sensing mode and observes a fluctuation of the complexsignal component of a reflected wave output from radar apparatus 2 forseveral tens of seconds, for example, at the distance and angle at whichan object is present.

If the fluctuation is regular and periodic and indicates a fluctuatingperiod that is regarded as breathing or heartbeat of a person,determiner 24 determines that the object is a living object. If theconditions described above are not satisfied, determiner 24 may regardthe object as a load and output a signal to vehicle control apparatus 90to perform control not to generate a warning.

When the engine of the vehicle stops and at least one or more occupantsrelease their seat belts, seat-belt wearing check apparatus 91 notifiesradar system 3 and vehicle control apparatus 90 of the result ofdetermination that the vehicle has arrived at the destination or thelike and that at least one or more occupants have exited the vehicle(finish of driving) (S107).

Mode switch 25 determines whether to switch to the living-object sensingmode on the basis of information from seat-belt wearing check apparatus91 about the vehicle (S108). If radar apparatus 2 senses a change in thenumber of sensed objects (YES in S108), radar system 3 performs theliving-object sensing mode (S109). The change in the number of sensedobjects includes a case where the number of objects is not changed as aresult of decreasing the number of objects and then increasing thenumber of objects.

If determiner 24 detects a fine movement resulting from heartbeat,breathing, and so on (YES in S110), determiner 24 determines that anoccupant or a pet (living object) is left in the passenger compartment,and notifies vehicle control apparatus 90 of the result.

Vehicle control apparatus 90 generates a left-behind warning inaccordance with the notification result (S111). Examples of theleft-behind warning include the blinking of a light, the releasing of adoor lock, and the transmission of email to a smartphone (communicationapparatus). If determiner 24 senses no living object in theliving-object sensing mode (NO in S110), determiner 24 determines thatno living object is left behind in the vehicle, and vehicle controlsystem 92 ends the process.

If determiner 24 determines that all the occupants left in the passengercompartment are children, vehicle control system 92 notifies vehiclecontrol apparatus 90 of information about a left-behind warning. If theoccupants left in the passenger compartment include an adult occupant,vehicle control system 92 may not notify vehicle control apparatus 90 ofinformation about the warning. Here, determiner 24 may determine anobject sensed by radar apparatus 2 in the living-object sensing modealso by taking into consideration the size of the object, and maydetermine that the object is an adult living object when the size of theobject is greater than or equal to a predetermined size.

Vehicle control apparatus 90 may also not perform warning when theoccupants left in the passenger compartment include an occupant (livingobject) in the driver's seat. The occupant in the driver's seat is anoccupant (living object) seated in the driver's seat from when thevehicle starts its movement to when the vehicle comes to a standstill.

Embodiment 7

This embodiment describes a radar system having a configuration in whichthe correctness of a result of sensing an object is fed back to anoccupant and is utilized to update training data, thereby improvingsensing performance. FIG. 29 is a diagram illustrating an exampleconfiguration of a radar system according to Embodiment 7.

Radar system 3 includes machine learner 26. Machine learner 26 comparesthe output of radar apparatus 2 with stored training data and determineswhether the output of radar apparatus 2 indicates an occupant ratherthan noise. Within the output of radar apparatus 2, data similar totraining data may be accumulated as new training data. When there is aplurality of pieces of training data, a piece of training data that isnot similar to the output of radar apparatus 2 may be deleted frommachine learner 26 for a predetermined period. Further, machine learner26 may add a weight to each of the plurality of pieces of training datain accordance with the actual comparison result of the training data fora predetermined period to add the confidence level of the training data.

In FIG. 29 , determiner 24 and mode switch 25 illustrated in FIG. 27 arenot illustrated. When radar system 3 illustrated in FIG. 29 is used invehicle control system 92 illustrated in FIG. 27 , determiner 24 andmode switch 25 can be additionally provided. In addition, machinelearning may also be applied to the output of determiner 24.

Next, the machine learning operation will be described. First, inresponse to the output of radar apparatus 2, machine learner 26erroneously determines that an occupant is seated in a seat (forexample, the front passenger's seat) in which no occupant is actuallyseated. Seat-belt wearing check apparatus 91 outputs to vehicle controlapparatus 90 a signal indicating, for each of the seats, whether theseat belt is worn (e.g., the seat belt for the front passenger's seat isnot worn).

Vehicle control apparatus 90 generates a wrong warning, indicating that“an occupant is seated in the front passenger's seat, but is not wearingthe seat belt”, from the determination result from radar system 3 andthe signal from seat-belt wearing check apparatus 91. The occupant (forexample, the driver) corrects the sensing result of radar system 3through user interface (UI) 93, for example, through a screen of a carnavigation system. Thereafter, machine learner 26 can delete thetraining data used in the current determination or reduce the confidencelevel.

On the other hand, if there is no feedback to UI 93 from the occupant,radar system 3 determines that occupants are correctly sensed. Then,radar system 3 uses the sensing result as training data and accumulatesthe sensing result in a memory of machine learner 26.

If a load is in a seat in which a radar apparatus senses an occupant, acorrection may be made, indicating that the object in the seat is a(non-living) load, instead of a simple correction being made, simplyindicating the wrong result. Accordingly, a radar system sets trainingdata indicating a case where a simple mistake has been made because ofno fine movement caused by a breathing or heartbeat and where an objectitself has been correctly sensed. To reduce the erroneous determinationdescribed above, the object sensing mode may be regularly changed to theliving-object sensing mode, and a determination may be made of whetheran object present in a seat is a living object or a load.

Additionally, it is also preferable that, after confirming that nooccupant is left in the vehicle, a user access vehicle control system 92from outside the vehicle by using, for example, a smartphone or the liketo cause a radar system to perform the object sensing mode and theliving-object sensing mode to learn a reference signal for non-presenceof an occupant.

OTHER EMBODIMENTS

Radar apparatus 2 or radar systems 3 a and 3 b according to Embodiments1 to 7 have been described, taking as an example a seat arrangementincluding two rows of seats, namely, front seat 51 and rear seat 52.However, in a seat arrangement including three rows of seats,Embodiments 1 to 7 may be applied to, for example, the first-row seatand the second-row seat, or Embodiments 1 to 7 may be applied to thesecond-row seat and the third-row seat. The same applies to four or morerows of seats.

Radar apparatus 2 according to Embodiments 1 to 7 is arranged inbackrest 19. Alternatively, radar apparatus 2 may be installed in aheadrest (not illustrated) coupled to backrest 19.

In the embodiments described above, the term “section” used to indicateeach constituent element may be interchangeably referred to as any otherterm such as “circuit (circuitry)”, “device”, “unit”, or “module”.

While various embodiments have been described with reference to thedrawings, it goes without saying that the present disclosure is notlimited to the foregoing examples. It is obvious that a person skilledin the art can conceive various modifications or variations within thescope set forth in the claims, and it is understood that suchmodifications or variations also fall within the technical scope of thepresent disclosure, as a matter of course. Further, any constituentelements in the embodiments described above may be combined asappropriate without departing from the spirit of the present disclosure.

The present disclosure can be implemented by software, hardware, orsoftware in cooperation with hardware. Each functional block used in thedescription of the embodiments described above may be partly or entirelyimplemented as a large-scale integration (LSI), which is an integratedcircuit, and each process described in the embodiments described abovemay be controlled partly or entirely by a single LSI or a combination ofLSIs. LSIs may be formed as individual chips or may be formed as asingle chip so as to include some or all of the functional blocks. TheLSI may include a data input and output. The LSI may be referred to asan IC, a system LSI, a super LSI, or an ultra LSI depending on adifference in the degree of integration. The technique of forming anintegrated circuit is not limited to the LSI and may be implemented byusing a dedicated circuit, a general-purpose processor, or aspecial-purpose processor. In addition, a field programmable gate array(FPGA), which is programmable after the manufacture of the LSI, or areconfigurable processor in which the connections and the settings ofcircuit cells inside the LSI can be reconfigured may be used. Thepresent disclosure may be implemented as digital processing or analogprocessing. If integrated circuit technology replaces LSI as a result ofthe advancement of semiconductor technology or other derivativetechnology, it goes without saying that the functional blocks may beintegrated using the integrated circuit technology.

The present disclosure can be implemented as any type of apparatus,device, and system (these are collectively referred to as communicationapparatuses) having communication functions. Non-limiting examples ofthe communication apparatuses include phones (such as mobile phones andsmartphones), tablet computers, personal computers (PCs) (such aslaptop, desktop, and notebook PCs), cameras (such as digital still/videocameras), digital players (such as digital audio/video players),wearable devices (such as wearable cameras, smartwatches, and trackingdevices), game consoles, digital book readers, telehealth andtelemedicine (remote healthcare and medicine prescription) devices,vehicles or transport systems (such as automobiles, airplanes, andships) with communication functions, and any combination of the variousapparatuses described above.

The communication apparatuses are not limited to portable or movablecommunication apparatuses and include any type of apparatus, device, andsystem that are non-portable or fixed. Examples of such communicationapparatuses include smart home devices (such as household electrical andelectronic equipment, lighting equipment, smart meters, and measurementequipment, and control panels), vending machines, and other “things”that may exist on Internet of Things (IoT) networks.

Communication includes data communication using cellular systems,wireless local-area network (LAN) systems, and communication satellitesystems, and data communication using a combination of these systems.The communication apparatuses also include devices such as controllersand sensors connected or coupled to communication devices that executethe communication functions described in the present disclosure. Forexample, the communication apparatuses include controllers and sensorsthat generate control signals or data signals used by communicationdevices that execute communication functions of the communicationapparatuses.

The communication apparatuses further include infrastructure equipmentthat communicates with the various non-limiting apparatuses describedabove or that controls the various apparatuses. Examples of theinfrastructure equipment include base stations, access points, and otherapparatuses, devices, and systems.

A radar apparatus according to an embodiment of the present disclosureincludes an antenna configured to radiate a first electromagnetic wavein a first radiation angle range including a first direction andradiates a second electromagnetic wave in a second radiation angle rangeincluding a second direction opposite to the first direction, and acircuit configured to detect a first target in the first direction and asecond target in the second direction on the basis of a first reflectedsignal of the first electromagnetic wave and a second reflected signalof the second electromagnetic wave, the first reflected signal and thesecond reflected signal being received by the antenna.

In the radar apparatus according to the embodiment of the presentdisclosure, the radar apparatus is provided in a first seat in an indoorspace; and the first direction is directed in a forward directionrelative to a backrest portion of the first seat, and the seconddirection is directed in a backward direction relative to the backrestportion of the first seat in the indoor space.

In the radar apparatus according to the embodiment of the presentdisclosure, the circuit includes a memory that stores the firstreflected signal and the second reflected signal in absence of the firsttarget and the second target, and the circuit is configured to detectthe first target and the second target on the basis of a differencebetween the first reflected signal received by the antenna and the firstreflected signal stored in the memory and a difference between thesecond reflected signal received by the antenna and the second reflectedsignal stored in the memory.

In the radar apparatus according to the embodiment of the presentdisclosure, the circuit is configured to detect the first target and thesecond target on the basis of at least one of body movement, heartbeat,or breathing indicated by the first reflected signal and at least one ofbody movement, heartbeat, or breathing indicated by the second reflectedsignal.

In the radar apparatus according to the embodiment of the presentdisclosure, the circuit is configured to determine whether each of thefirst target and the second target is detectable, on the basis of areflected signal from a reference indicator arranged in the indoor spacein accordance with arrangement of the first seat and the second seat.

In the radar apparatus according to the embodiment of the presentdisclosure, the circuit is configured to determine whether each of thefirst target and the second target is detectable, on the basis of adetection result of at least one of an angle sensor that detects areclining angle of the first seat and/or a position sensor that detectsa sliding position of the first seat in a forward or backward direction.

In the radar apparatus according to the embodiment of the presentdisclosure, the antenna includes a first antenna element group arrangedon a first surface of a substrate, and the first direction is adirection extending in a direction normal to the first surface.

In the radar apparatus according to the embodiment of the presentdisclosure, a portion of the substrate where the first antenna elementgroup is provided has a smaller thickness than a rest of the substrate.

In the radar apparatus according to the embodiment of the presentdisclosure, the substrate includes a wave director on a second surfacethereof, the second surface being a surface of the substrate opposite tothe first surface.

In the radar apparatus according to the embodiment of the presentdisclosure, the antenna includes a second antenna element group arrangedon a second surface of the substrate, the second surface being a surfaceof the substrate opposite to the first surface.

In the radar apparatus according to the embodiment of the presentdisclosure, the number of antenna elements in the first antenna elementgroup is different from the number of antenna elements in the secondantenna element group.

A vehicle according to an embodiment of the present disclosure includesthe radar apparatus according to the embodiment of the presentdisclosure, and a seat including a backrest portion and a headrestportion. The antenna of the radar apparatus is provided in the backrestportion or the headrest portion. A radiation direction of the firstelectromagnetic wave is directed in a forward direction relative to thebackrest portion or the headrest portion, and a radiation direction ofthe second electromagnetic wave is directed in a backward directionrelative to the backrest portion or the headrest portion.

INDUSTRIAL APPLICABILITY

The present disclosure is suitable for use in an occupant detectionsensor in a passenger compartment of a vehicle.

REFERENCE SIGNS LIST

-   -   2 (2 a to 2 m) Radar apparatus    -   3 (3 a to 3L) Radar system    -   4 Sunroof    -   6 Substrate    -   7 Antenna    -   8 Radar chip    -   9 Radome    -   10 Cavity    -   11, 12 Electromagnetic beam    -   13 Wave director    -   14 Via    -   15 Wiring    -   16 Reflecting plate    -   17 Antenna element    -   18 Angle sensor    -   19 Backrest of seat    -   20 Reference mark    -   21 Radio-wave absorber    -   22 Reference mark    -   24 Determiner    -   25 Mode switch    -   26 Machine learner    -   27 Antenna    -   27 a to 27 n Antenna element    -   31 First direction    -   32 Second direction    -   41, 42 Occupant    -   51 Front seat    -   52 Rear seat    -   72 Antenna    -   80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 80 a, 80 b, 80 c, 80 d        Reflector    -   90 Vehicle control apparatus    -   91 Seat-belt wearing check apparatus    -   92 Vehicle control system    -   93 UI

What is claimed is:
 1. An object detection apparatus in a vehicle, theobject detection apparatus comprising: one or more sensors configured todetect at least one object located on at least three rows of seats inthe vehicle, each of the one or more sensors being positioned on aceiling above at least one of the at least three rows of seats in thevehicle but not above all of the at least three rows of seats; and acircuit configured to determine whether or not the at least one objectdetected is a living-object, wherein a number of the one or more sensorsis less than a number of the at least three rows of seats.
 2. The objectdetection apparatus according to claim 1, wherein the circuit is furtherconfigured to determine either a start of driving of the vehicle, arestart of driving of the vehicle, and an end of driving of the vehicle,and wherein when the circuit determines that the start of driving of thevehicle or the restart of driving of the vehicle, the circuit instructsthe one or more sensors to operate in an object sensing mode to detect apresence or an absence of the at least one object, and when the circuitdetermines that the end of driving of the vehicle, the circuit instructsthe one or more sensors to operate in a living-object sensing mode todetect whether or not the at least one object is the living-object. 3.The object detection apparatus according to claim 1, wherein, when thecircuit determines that the at least one object detected is theliving-object, the circuit instructs a vehicle control device connectedto the vehicle to notify outside of the vehicle that the living-objectis left in the vehicle.
 4. The object detection apparatus according toclaim 1, wherein the one or more sensors include two sensors, the atleast three rows of seats include a first row of seats, a second row ofseats and a third row of seats, a first sensor of the two sensorsdetects the at least one object on the first row of seats and the secondrow of seats from the ceiling above the first row of seats, and a secondsensor of the two sensors detects the at least one object on the thirdrow of seats from the ceiling above the third row of seats.
 5. Theobject detection apparatus according to claim 1, wherein the one or moresensors include two sensors, the at least three rows of seats include afirst row of seats, a second row of seats and a third row of seats, afirst sensor of the two sensors detects the at least one object on thefirst row of seats from the ceiling above the first row of seats, and asecond sensor of the two sensors detects the at least one object on thesecond row of seats and the third row of seats from the ceiling abovethe second row of seats.
 6. The object detection apparatus according toclaim 4, wherein the first sensor of the two sensors detects the atleast one object on the first row of seats and the second row of seatsfrom above a driver's seat in the first row of seats.
 7. The objectdetection apparatus according to claim 1, wherein the one or moresensors include one sensor, and the one sensor has a maximum viewingangle of 160 degrees.
 8. The object detection apparatus according toclaim 5, wherein the first sensor has a concave lens.
 9. The objectdetection apparatus according to claim 5, wherein the first sensor hasmultiple concave-convex lenses.
 10. The object detection apparatusaccording to claim 1, wherein the one or more sensors include onesensor, the at least three rows of seats include a first row of seats, asecond row of seats and a third row of seats, the one sensor detects theat least one object on the first row of seats using reflected waves froma rear-view mirror or side-view mirrors, and the one sensor detects theat least one object on the second row of seats and the third row ofseats using direct waves from the ceiling above the second row of seats.11. The object detection apparatus according to claim 7, wherein the onesensor has a first direction that scans using a direct wave and a seconddirection that scans using a reflector, and the first direction isdifferent from the second direction.
 12. The object detection apparatusaccording to claim 1, wherein the one or more sensors have a drivingcircuit that changes a sensing direction.
 13. The object detectionapparatus according to claim 1, wherein the one or more sensors have adrive circuit that changes an installation position of the one or moresensors.
 14. The object detection apparatus according to claim 1,wherein the one or more sensors include one sensor, and the one sensordetects the at least one object on a first row of seats among the atleast three rows of seats using reflected waves that are reflected froma windshield of the vehicle.
 15. The object detection apparatusaccording to claim 1, further comprising: a reflector placed above afirst row of seats among the at least three rows of seats, wherein theone or more sensors include one sensor, and the one sensor detects theat least one object located on the first row of seats using reflectedwaves from a reflector.
 16. The object detection apparatus according toclaim 1, wherein the at least three rows of seats include a first row ofseats, a second row of seats and a third row of seats, the objectdetection apparatus further comprises a reflector placed at a top of thethird row of seats, the one or more sensors include one sensor, the onesensor detects the at least one object on the first row of seats and thesecond row of seats without using reflected waves from a reflector, andthe one sensor detects the at least one object on the third row of seatsusing reflected waves from a reflector.
 17. The object detectionapparatus according to claim 1, wherein the at least three rows of seatsinclude a first row of seats, a second row of seats and a third row ofseats, the object detection apparatus further comprises one or moreelongated reflectors are placed at an edge of the ceiling above thesecond row of seats and the third row of seats, the one or more sensorsinclude one sensor, and the one sensor detects the at least one objectlocated on the first row of seats by using a direct wave from theceiling above the first row of seats, and detects the at least oneobject located on the second row of seats and the third row of seats byusing a reflected wave that is reflected from the one or more elongatedreflectors.